As I write in this weekend’s Journal, falling home prices and lethargic sales have given a boost to the apartment sector, with plenty of people willing to become landlords. With millions of families switching from being homeowners to renters, apartment-building values have soared.

That isn’t good for renters, who enjoyed falling rents, landlord concessions and even offers of incentives such as flat-screen televisions to sign leases after the recession hit the housing market. Those days appear to be over. Now, rents are rising and vacancies are falling in many markets, making it harder to find a place.

Just ask Lindsey Neiling. The 23-year-old Chicago resident is facing a rent increase to $765 from $720 on her studio apartment when her lease is up in April. “They know they can get more for my unit,” she says. In Washington, you have to make quick decisions because apartments aren’t staying vacant for long, says Cameron Hardesty.

Resurgent apartment values were first seen in late 2009 in markets such as New York City and Washington, D.C., where the economy has held up better and recoveries have been quicker. But the improvement has now spread to other markets including Los Angeles, Seattle, Boston, Baltimore and Austin, Texas. There’s even demand in hard-hit Las Vegas, where plenty of foreclosed homes are up for rent.

“Buyers are swarming for any kind of multifamily product,” says Rick Hildreth, a senior adviser with the Land Advisors Organization. “As soon as it’s being put on the market, it’s just getting scooped up in pretty high numbers.”

To be sure, not all apartment markets are booming. Houston, Jacksonville, Fla., and Memphis, Tenn., had fourth-quarter vacancy rates topping 10%. Still, market forces are expected to keep pushing rents higher. Green Street Advisors expects every major metro market to see rent growth between 3% and 10% this year, with the biggest gains in San Jose, Calif., San Francisco and New York City.

Apartment values are being helped by powerful supply-and-demand forces. Renter households now top a record 37 million after increasing more than 3.5 million in the past five years. Green Street expects another 4.4 million rental households to be added by 2015.

Many home owners bruised by the housing crash are opting to rent. “A lot of people now realize that home prices do go down, and they go down a significant amount,” says CoStar’s Chris Macke. “There has been a change in attitude” about renting.

As a result, the nation’s home-ownership rate, which topped 69% in 2004, is falling. It came in at 66.5% for the fourth quarter, the Census Bureau said Monday. Each 1% decline represents 1 million households moving to rentals, housing experts say.

Job growth may also be boosting demand for apartments, particularly among 25-to-34-year-olds, a group known as big renters. The group has garnered the lion’s share of new jobs, emboldening people who had been sharing units or living with parents to get their own apartments, says Andrew McCulloch, a Green Street analyst. No twenty-something wants to return to mom and dad’s curfew, while some of those roomies taken on during the downturn are probably getting annoying.

This comes as the new supply of apartment buildings is at its lowest level in two decades because the financing spigot turned off when the recession hit. Apartment completions will total 53,000 this year, half of what was delivered in 2010, according to Marcus & Millichap, and down from 120,000 in the peak year of 2009.

Landlords’ upper hand could be lost once new supply being started now hits the market. CoStar expects nearly 95,000 units to be delivered in 2012 and more than 109,000 in 2013.